<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
  </head>
  <body>
    <div id="root">
      <h2>今天天气很{{info}}</h2>
      <button @click="changeWeather">切换天气</button>
      <hr />
      <h3>a的值时：{{numbers.a}}</h3>
      <button @click="numbers.a++">点我让a加1</button>
    </div>

    <script>
      const vm = new Vue({
        el: "#root",
        data: {
          isHot: true,
          numbers: {
            a: 1,
            b: 1,
          },
        },
        computed: {
          info() {
            return this.isHot ? "炎热" : "凉爽";
          },
        },
        methods: {
          changeWeather() {
            this.isHot = !this.isHot;
          },
        },
        watch: {
          isHot: {
            handler() {
              console.log("发生变化");
            },
          },
          numbers: {
            deep: true,
            handler() {
              console.log("numbers被改变了！");
            },
          },
        },
      });
    </script>
  </body>
</html>
